In recent years, a technique of attaching an input device referred to as a touch panel or a touch sensor to a display surface side of a display device and detecting and outputting an input position when input operations are performed by contacting the touch panel with a finger or an input tool such as a touch pen has been known. Such display devices having a touch panel are widely used in portable information terminals such as mobile phones in addition to computers.
One detecting method for detecting contact positions at which a finger or the like has contacted the touch panel is the electrostatic capacitance method. In an electrostatic capacitive touch panel, a plurality of capacitive elements each made up of a pair of electrodes disposed to be opposed to each other with a dielectric layer interposed therebetween, that is, a driving electrode and a sensing electrode are provided in a plane of the touch panel. Then, the input positions are detected by utilizing the characteristics that the electrostatic capacitance of capacitive elements changes when performing input operations by contacting the capacitive elements with a finger or an input tool such as a touch pen.
In the display device to which an input device such as a touch panel is attached, it is desirable to reduce electric resistance of the sensing electrodes for improving the detection performance, and thus a conductive film such as a metal film is sometimes used as a material of the sensing electrode. Thus, in an electrode substrate included in the display device and formed of a base and the sensing electrode formed on the base, a protective film is formed so as to cover the sensing electrode for preventing corrosion of the sensing electrode. At this time, for example, a protective film is formed by applying coating liquid by the use of an ink jet method so as to cover the sensing electrode formed on the substrate and then curing a coating film formed of the applied coating liquid.
As the method of applying the coating liquid by the use of the ink jet method, for example, Japanese Patent Application Laid-Open Publication No. 8-227012 (Patent Document 1) and Japanese Patent Application Laid-Open Publication No. 9-203803 (Patent Document 2) each describe a method of forming a color filter of a liquid crystal display device by an ink jet method. In addition, Japanese Patent Application Laid-Open Publication No. 2008-183489 (Patent Document 3) describes a method of forming a desired pattern by forming a lyophilic region and a repellant region on a surface of a substrate and then discharging liquid drops to the surface of the substrate by the use of an ink jet method. Further, Japanese Patent Application Laid-Open Publication No. 2011-145535 (Patent Document 4) describes a method of forming an alignment film of a liquid crystal display device by an ink jet method.